Generally, a suspension system supports the weight of a vehicle and absorbs and dampens out road shocks. The suspension system, therefore, allows the vehicle to travel over rough surfaces with minimal up and down body movement. This improves the vehicle ride of the occupants and load in the vehicle and reduces dynamic stress of each portion of the vehicle body and wheel vibration, thereby increasing the driving stability.
An Active Geometry Controlled Suspension (AGCS) system among the suspension systems adjusts the rear wheels to a toe-in setting during the turn by elongating or shortening the length of a rear control arm, thereby minimizing the vehicle roll and improving the maneuverability.
An AGCS Electronic Control Unit (ECU) pre-determines the bump of the vehicle by receiving detection values from a steering angle sensor and vehicle speed sensor to thereby obtain a steering stability against the bump on exterior wheels when the vehicle makes a turn. Then, the AGCS ECU provides battery power to an actuator of the exterior rear wheel through a switched relay to operate the actuator, thereby obtaining the steering safety by toe-in adjustment of the exterior rear wheels.
However, there is a drawback in that as the conventional AGCS system provides the battery power to the actuator of the rear wheels to operate the actuator, when the load of the battery power varies (particularly, when an instantaneous power drop occurs while switching on the air-conditioner or lights), the greatly varied battery voltage is transmitted to the actuator and changes the operation speed of the actuator, thus destabilizing the steering of the vehicle.